By now you've probably read or heard something about the glycemic index (GI), for example, how using the index to make food choices may help prevent and manage certain diseases, such as type 2 diabetes and heart disease. Many health organizations, including the Canadian Diabetes Association and the World Health Organization, support the use of the GI for individuals with diabetes.
But the GI is becoming an increasingly hot nutritional concept for people who don't already suffer from a chronic disease. Many prominent nutrition researchers and dietitians see it as a promising approach to healthy eating and the prevention and treatment of some chronic diseases.
The GI is a valid and potentially useful concept, but it is also complex and can be difficult to follow. Because the science around the GI is still quite young, there are some unanswered questions. As the science evolves, and researchers learn more about the GI and its role in the prevention and treatment of chronic diseases, these questions will be answered. Until then, here is a no-nonsense, nuts-and-bolts approach to incorporating GI principles into your family's diet.
Q. What is the glycemic index?
Developed in the early 1980s by Dr. David Jenkins, a professor of nutritional sciences and medicine at the University of Toronto and a doctor at
St. Michael's Hospital in Toronto, the glycemic index ranks carbohydrate-containing foods according to how they affect blood glucose, or sugar, levels. The index measures how much your blood sugar rises after you eat a specific food; the higher the number, the greater the blood sugar response. Pure glucose is used as a reference food (it raises blood sugar the quickest) and is assigned the arbitrary value of 100. All other foods are then given a number relative to it.
Q. How does it work?
The GI value of a food is determined by the speed at which your body breaks it down and converts it into glucose, or sugar, which is your body's main source of energy. High-GI foods are broken down quickly, causing a rapid rise in blood sugar, whereas low-GI foods take longer to break down, causing a slow, steady rise in blood sugar.
Q. What are the health benefits of eating low-GI foods?
Research has shown that eating foods with a low GI may:
Help prevent obesity. Low-GI foods may fill you up quickly and, because they're digested more slowly, stay in your stomach longer, making you feel full longer. As a result, you may end up eating less and consuming fewer calories. Because it is energy balance that keeps your weight in check (calories in equal calories out), consuming fewer calories may prevent you from putting on unwanted pounds.
Help prevent type 2 diabetes. Type 2 diabetes is a condition in which blood sugar levels are higher than normal. It is caused by a lack of insulin, the hormone that helps your cells break down carbohydrates into sugar for energy. If you have diabetes, either your pancreas doesn't make enough insulin and/or your cells don't respond to the insulin. As a result, sugar in the blood can't enter the cells, and they become starved for energy while your blood sugar remains high. Because high-GI foods may increase insulin demand and raise the workload of the pancreas, some researchers think that many years of eating a diet rich in high-GI foods may cause the pancreas to wear out, resulting in type 2 diabetes. Eating low-GI foods can help reduce the demand on the pancreas so it doesn't have to work too hard.
Help manage diabetes by controlling blood sugar and improving the body's sensitivity to insulin. Low-GI foods aren't converted to sugar as quickly as high-GI foods, so they may keep your blood sugar from spiking, which means your body can keep up with insulin demands. Keeping blood sugar levels under control is especially important for people with diabetes to avoid the serious complications of the disease.
Help prevent heart disease. Elevated insulin levels may be one of the promoting factors for heart disease. High-GI foods produce high spikes in blood sugar and insulin demand. This may raise your cholesterol and triglyceride levels, which can contribute to heart disease. On the other hand, consuming low-GI foods keeps blood sugar and insulin levels in check, thereby reducing your total blood cholesterol and LDL, or "bad," cholesterol, while increasing your heart-friendly HDL, or "good," cholesterol.
